A wideband O2 sensor just doesn't work very well in a 2 stroke. The oil is the number one problem. (contaminates and ruins the sensor). Another is the way a tuned pipe 2 stroke works...unburned air/fuel leave the engine, and are then returned by the sonic waves in the pipe. When this unburned air/fuel hits the O2 sensor, it will give erroneous readings. (this can be prevented by installing it downstream of the stinger, but you can't do that in a watercraft that has water injected there) Also, what A/F ratio do you think you should be shooting for? It's not really about A/F ratio with a 2 stroke anyway...its about keeping the piston just cool enough to keep it from melting, and piston wash will show you what you need to know. Stick with rpm tuning, piston wash, plug chops, and EGTs (if you're inclined to do so..not a huge fan here either). I've tuned lots fast 2 strokes, and I've never used a WB O2 here...I do use one on my Procharged LS2, however...they are not all they're cracked up to be in that application either.